SM U-3 was the third German U-boat created by the German Empire in their history, and the first of two submarines in its class. The boat was built by Kaiserliche Werft Danzig and was launched on 27 March 1909. U-3 began her career in World War I as a training boat from 1 August 1914 to 11 November 1918. On 1 December 1918, the surrendered boat was being towed to Preston to be broken up when she sank. Unlike the first two U-boat designs, the third design was fitted with a SK L/40 deck gun.
*List of U-boats of Germany